The collaboration is open to all Canadian HIV treatment cohorts with more than 100 eligible patients [14]. Patient selection and data extraction were performed at the data centres Selleckchem ATM inhibitor of the participating cohort sites. Data used in this analysis were from nine cohorts of HIV-positive individuals in British Columbia, Ontario and Quebec. In provinces with multiple cohorts, viral load data were entered from each cohort site and not from a provincial data source. Data from the contributing cohorts were combined into a single data set at the data co-ordinating centre

in Vancouver. Further details of the participating cohorts and the CANOC structure have been previously published [14,15]. CANOC eligibility criteria include documented HIV infection, residence in Canada, age 19 years and over, initiation of three or more antiretroviral drugs for the first time (i.e. antiretroviral-naïve HAART start) on or after 1 January 2000, and a documented HIV-1 RNA measurement and CD4 cell count within 6 months prior to the start of therapy. To be included in this analysis, individuals had to have at least two viral load measurements after

starting HAART. Moreover, only individuals whose baseline viral loads were ≥50 copies/mL were included. Loss to follow-up among patients http://www.selleckchem.com/products/sotrastaurin-aeb071.html included in this analysis was defined as no contact for at least 1 year. The primary endpoint was the achievement of viral load suppression, defined as the time to the first of at least two consecutive HIV-1 plasma RNA measurements below 50 HIV-1 RNA copies/mL. Event-free subjects were censored at the date of last available viral load measurement occurring prior to 31 December 2008. Viral load monitoring among eligible participants occurred a median of 4.0 times per year [interquartile range (IQR) 3.1–5.3]. In preliminary analyses,

patient characteristics were compared by whether or not they ever achieved BCKDHA virological suppression. Categorical variables were compared between groups using the Pearson χ2 test or the Fisher exact test and continuous variables were compared using the Wilcoxon rank-sum test. Baseline data were obtained within the 6 months prior to HAART initiation. As the use of viral load assays varied by region and over time, all measures were buffered to a maximum value of 100 000 copies/mL. In the analysis of time to virological suppression, stratified life table and Kaplan–Meier methods were used to compare time to suppression by drug class of initial therapy. The data did not meet Cox, Weibull or exponential hazard regression assumptions. Thus, piecewise survival exponential models were used to investigate the effects of covariates on time to virological suppression.